MCQ 1

A moving charge is surrounded by:

Options
1. 2 fields ✅
2. 3 fields
3. 4 fields
4. None of these

Explanation:

1. A moving charge generates both an electric field and a magnetic field.
2. These two fields coexist around the charge as it moves.

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MCQ 2

A photon while passing through a magnetic field is deflected towards:

Options
1. North pole
2. South pole
3. Are ionized
4. None of these ✅

Explanation:

1. Photons are electrically neutral particles.
2. As they have no charge, they do not interact with magnetic fields and hence remain undeflected.

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MCQ 3

Magnetism is related to:

Options
1. Stationary charges
2. Moving charges ✅
3. Stationary and moving charges
4. Law of motion

Explanation:

1. Magnetism arises from moving charges, as stationary charges only produce electric fields.

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MCQ 4

When a charged particle enters a magnetic field perpendicularly, the path followed by it is:

Options
1. A helix
2. A circle ✅
3. A straight line
4. An ellipse

Explanation:

1. The magnetic force acts as a centripetal force, causing the charged particle to move in a circular path.

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MCQ 5

The torque in a coil can be increased by increasing:

Options
1. Number of turns
2. Current and magnetic field
3. Area of the coil
4. All of the above ✅

Explanation:

1. Torque in a coil is given by:

$$\tau = N B I A \cos \theta$$

Increasing $N$, $I$, $B$, or $A$ increases the torque.

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MCQ 6

The magnetic flux will be maximum for an angle of:

Options
1. $0^\circ$ ✅
2. $60^\circ$
3. $90^\circ$
4. $160^\circ$

Explanation:

1. Magnetic flux is given by:

$$\Phi = B A \cos \theta$$

Flux is maximum when $\theta = 0^\circ$, as $\cos 0^\circ = 1$.

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MCQ 7

The Weber is a unit of measure for:

Options
1. Conductance
2. Electric current
3. Magnetic flux ✅
4. Electric flux

Explanation:

1. The Weber (Wb) measures magnetic flux and is defined as:

$$\mathrm{Wb} = \frac{\mathrm{N} \cdot \mathrm{m}}{\mathrm{A}}$$

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MCQ 8

One Weber is equal to:

Options
1. $\mathrm{N \cdot A^2 / m}$
2. $\mathrm{N \cdot m^2 / A}$ ✅
3. $\mathrm{N \cdot A / m}$
4. $\mathrm{N \cdot m / A}$

Explanation:

1. Magnetic flux is expressed as:

$$\Phi = B \cdot A$$

Its unit is:

$$\frac{\mathrm{N \cdot m}}{\mathrm{A}}$$

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MCQ 9

An electron moves at $2 \times 10^2 \, \mathrm{m/s}$ perpendicular to a magnetic field of $2 \, \mathrm{T}$. What is the magnitude of the magnetic force?

Options
1. $1 \times 10^{-6} \, \mathrm{N}$
2. $6.4 \times 10^{-17} \, \mathrm{N}$
3. $3.6 \times 10^{-24} \, \mathrm{N}$ ✅
4. $4 \times 10^6 \, \mathrm{N}$

Explanation:

1. Force is given by:

$$F = q v B \sin \theta$$

2. Substituting $q = 1.6 \times 10^{-19} \, \mathrm{C}$, $v = 2 \times 10^2 \, \mathrm{m/s}$, $B = 2 \, \mathrm{T}$, and $\sin 90^\circ = 1$:

$$F = 1.6 \times 10^{-19} \times 2 \times 10^2 \times 2 = 3.6 \times 10^{-24} \, \mathrm{N}$$

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MCQ 10

The force on a charged particle moving parallel to a magnetic field is:

Options
1. Maximum
2. Minimum
3. Zero ✅
4. None of these

Explanation:

1. The force on a charged particle in a magnetic field is:

$$F = q v B \sin \theta$$

When $\theta = 0^\circ$, $\sin 0^\circ = 0$, so $F = 0$.

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MCQ 11

Ampere’s law is applicable to:

Options
1. Circular path
2. Rectangular path
3. Any closed path ✅
4. None of these

Explanation:

1. Ampere’s law states:

$$\oint \vec{B} \cdot \mathrm{d}\vec{l} = \mu_0 I$$

This applies to any closed loop.

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MCQ 12

The unit of permeability of free space is:

Options
1. $\mathrm{T \cdot m / A}$ ✅
2. $\mathrm{T \cdot m^2 / A}$
3. $\mathrm{T \cdot m / A^2}$
4. None of these

Explanation:

1. Permeability of free space ($\mu_0$) is:

$$\mu_0 = 4 \pi \times 10^{-7} \, \mathrm{T \cdot m / A}$$

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